Systemic sclerosis (SSc, also known as scleroderma) is a disease characterized by fibrosis of the skin and organs, inflammation, and an abnormal endothelial cell lining inside of vessels. A common and deadly complication of SSc is pulmonary hypertension (PH), which is an abnormal elevation in the blood pressure within the lung blood vessels. Early identification and treatment of PH is important in SSc, and no clinical factors can predict which patients will develop PH with acceptable accuracy. A potential marker of PH in SSc is the presence of increased amounts of endothelial microparticles (EMPs), which are substances circulating in the blood that were released from damaged vessel wall endothelial lining. A main goal of this study is to investigate if there is a difference in EMP levels between SSc patients with and without PH. The investigators will also use human endothelial cells in a lab environment to test whether these EMPs isolated from SSc patients are actually causing damage to the vessel lining. Lastly, the investigators will investigate the potential benefit of a medication used after transplant, mycophenolate mofetil (MMF). This will be done by causing damage to isolated human endothelial cells and treating them with MMF. The main goal of this portion of our study is to see if EMP levels are reduced when cells are treated with MMF. Overall, the investigators anticipate the following outcomes of this study: 1) use EMP levels to differentiation patients with SSc who have PH from those without PH, 2) use EMPs to understand how endothelial damage occurs in SSc, and 3) use EMPs to help us develop new treatments for patients with vascular diseases.

For systemic sclerosis subjects:

Inclusion Criteria:

• Age >18 years
• Meet American College of Rheumatology criteria for systemic sclerosis

Exclusion Criteria:

• Chronic kidney disease (estimated creatinine clearance <50mL/min)
• Uncontrolled hypertension (diastolic blood pressure>120mmHg)
• Acute coronary syndrome within the past 6 months
• Chronic obstructive pulmonary disease
• Diabetes mellitus
• Hemolytic anemia
• Active tobacco abuse

For healthy control subjects:

Inclusion Criteria:

• Age>18 years
• Age- and sex-matched to SSc patients

Exclusion criteria:

• Coronary artery disease
• Uncontrolled hypertension (diastolic blood pressure>120mmHg)
• Chronic obstructive pulmonary disease
• Chronic kidney disease
• Diabetes mellitus
• Hemolytic anemia
• Active tobacco abuse

There will be 3 groups: systemic sclerosis subjects with pulmonary hypertension, systemic sclerosis subjects without pulmonary hypertension, and healthy age- and sex-matched controls.